Forced convection gas oven

ABSTRACT

The invention concerns a forced convection gas oven wherein a globally parallelepiped muffle chamber ( 1 ) contains a centrifugal convection turbine ( 9 ) driven by a motor ( 10 ) and arranged adjacent to the centre of the rear peripheral wall ( 7 ). A gas burner ( 14 ) is arranged coaxially upstream of the turbine, the assembly being surrounded by a mechanical protection grid ( 22 ). The gas burner ( 14 ) is annular in shape and is oriented towards the centre of the convection turbine ( 9 ). The oven is thus provided both with a better performance and a better distribution of cooking heat.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to ovens for cooking food, and moreparticularly forced convection gas ovens used in institutional kitchens.

[0002] Forced convection gas ovens for cooking food generally comprise ametal muffle surrounding an interior muffle cavity, with a lower wallforming a floor, an upper wall forming a ceiling, and four verticalperipheral walls. At least one of the peripheral walls is provided withan access door for introducing food to be cooked into the interiorcavity of the muffle and extracting it therefrom.

[0003] In the interior space of the oven, i.e. in the interior cavity ofthe muffle, convection of air is achieved by a convection turbine, thatis driven in rotation by a motor, and that is generally disposed in thevicinity of one of the peripheral walls that has no access door. Theturbine is mounted to rotate about a rotation axis perpendicular to theperipheral wall.

[0004] Gas burners are placed in the flow of air, upstream or downstreamof the turbine, and are adapted to heat the air propelled into themuffle by the turbine, encouraging the cooking of the food.

[0005] In prior art gas ovens, for example as described in the documentEP 0 733 862 A, the interior cavity of the muffle is divided into twocompartments: a cooking compartment, accessible via the door, andconformed to receive the food to be cooked, and a heating compartment,containing the convection turbine and the gas burners. The cookingcompartment is always isolated from the heating compartment by aseparating wall, that is generally perpendicular to the rotation axis ofthe turbine. The separating wall has a double effect of channeling theflow of air propelled by the turbine, and protecting the heatingcompartment from splashed grease and other materials from the food beingcooked. In fact, in prior art ovens, a constant concern is preventingsplashes from food being cooked soiling the members inside the heatingcompartment, namely the turbine, the gas burners and sensors used tocontrol these elements.

[0006] Despite the presence of the separating wall, manual cleaningoperations are periodically required to guarantee that the oven isclean. Cleaning cannot be automated in the prior art oven structures,and necessitates demounting and remounting the separating wall.

[0007] Another problem that is encountered in gas ovens of this kind forcooking food is the difficulty of ensuring regular cooking of all thefood in the oven, regardless of its position within the cookingcompartment. It is found in fact that the cooking of the food can varysignificantly as a function of the position of the food in the cookingcompartment. Some areas of the cooking compartment can overheat thefood, while other areas achieve insufficient heating. Also, the evennessof cooking is modified as a function of the type of food to be cooked,and as a function of the quantities of food introduced into the cookingcompartment. This results in uneven cooking, and reduced efficiency.

SUMMARY OF THE INVENTION

[0008] A particular object of the present invention is to avoid thedrawbacks of prior art structures of forced convection gas ovens forcooking food, with the aim of achieving more even cooking and improvedefficiency.

[0009] The invention stems from the surprising observation that aparticular disposition of the gas burner achieves more even cooking andimproved efficiency.

[0010] Accordingly, to achieve the above and other objects, theinvention proposes a forced convection gas oven for cooking food, theoven comprising:

[0011] a muffle with a generally parallelepipedal interior cavitydelimited by a lower floor wall, an upper ceiling wall and fourperipheral walls, at least one of the peripheral walls being providedwith an access door for entry of food to be cooked into the interiorcavity of the muffle and its exit therefrom,

[0012] a centrifugal convection turbine, driven in rotation by a motor,disposed in the interior cavity of the muffle in the vicinity of thecenter of an adjacent peripheral wall with no access door, mounted torotate about a rotation axis perpendicular to the adjacent peripheralwall, and adapted to aspirate air axially toward the center of theadjacent peripheral wall and to discharge it radially toward the edgesof the adjacent peripheral wall,

[0013] a gas burner placed axially in the aspiration inlet of theconvection turbine, and adapted to heat the air that is propelled intothe muffle by the convection turbine to cook the food,

[0014] a cooking volume, reserved in the interior cavity of the muffleto receive food to be cooked;

[0015] according to the invention, the gas burner is directed towardsaid peripheral wall of the oven, at which wall the convection turbineis adjacent, and the gas burner is directed toward the center of theconvection turbine.

[0016] The turbine can advantageously have a generally cylindricalstructure, with a posterior flange carrying a plurality of short bladesat the front and distributed around its periphery.

[0017] The diameter of the convection turbine can advantageously begreater than one third of the larger dimension of the adjacentperipheral wall.

[0018] In one advantageous embodiment, the gas burner is generallyannular, and its axis is substantially horizontal and perpendicular tosaid adjacent peripheral wall.

[0019] For example, the gas burner comprises a posterior heating plate,with holes through which gas can flow distributed over its surface, andshutting off an annular cavity in a burner body.

[0020] A burned gas evacuation pipe, through which the burned gasesescape axially away from the adjacent peripheral wall and are thenguided toward the upper portion of the oven, advantageously passesthrough the central passage of the gas burner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other objects, features and advantages of the present inventionwill emerge from the following description of particular embodiments ofthe invention, which is given with reference to the appended drawings,in which:

[0022]FIG. 1 is a perspective view of one embodiment of an ovenaccording to the invention;

[0023]FIG. 2 is a front view of the FIG. 1 oven;

[0024]FIG. 3 is a side view of the FIG. 2 oven, in section taken alongthe line B-B in FIG. 2;

[0025]FIG. 4 is a perspective view of one embodiment of the gas burneraccording to the invention; and

[0026]FIG. 5 is a side view in diametral section of the FIG. 4 gasburner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] In the embodiment depicted in the figures, a convection ovenaccording to the invention comprises a muffle 1, having an interiorcavity 8 of generally parallelepipedal shape delimited by a bottom floorwall 2, a top ceiling wall 3, two opposite lateral peripheral walls 4and 5, an anterior peripheral wall 6 and a posterior peripheral wall 7.

[0028] The anterior peripheral wall 6 is fitted with an access door forintroducing food to be cooked into the interior cavity 8 of the muffleand extracting it therefrom.

[0029] The interior faces of the walls of the muffle are generallysmooth, to prevent sticking and retention of food particles liable to beseparated from food to be cooked.

[0030] A convection turbine 9 is driven in rotation by a motor 10supplied with power by an external electrical power supply. Theconvection turbine 9 is of the centrifugal type, aspirating air axiallyvia its center and discharging air radially via its periphery. To thisend it comprises inclined blades, in the usual manner known in the art.The convection turbine 9 is disposed in the vicinity of the center of aperipheral wall with no access door. In the embodiment shown, theconvection turbine 9 is disposed in the vicinity of the center of theposterior peripheral wall 7 of the muffle.

[0031] Alternatively, in an embodiment that is not depicted in thefigures, an oven can be provided to have two opposite doors respectivelyformed in the anterior peripheral wall 6 and in the posterior peripheralwall 7, with the turbine placed in the vicinity of one of the oppositelateral peripheral walls 4 and 5 of the oven.

[0032] The convection turbine 9 is mounted to rotate about a rotationaxis 11 perpendicular to the posterior peripheral wall 7 to which it isadjacent.

[0033] Accordingly, the convection turbine 9 aspirates air axiallytoward the center of the posterior peripheral wall 7 and discharges airradially toward the edges of the posterior peripheral wall 7.

[0034] According to the invention, the heating means comprise a gasburner 14, placed axially in the aspiration inlet of the convectionturbine 9, and adapted to heat the air that is propelled into the muffleby the convection turbine 9. The gas burner 14 is directed toward theposterior wall 7 of the oven, i.e. directs the flame that it producestoward the posterior wall 7 of the oven. Simultaneously, the gas burner14 is directed toward the center of the turbine 9, i.e. directs theflame that it produces toward the center of the turbine 9. It issupplied via a supply pipe 16. A pipe 17 for evacuating burned gasespasses through its central portion.

[0035]FIGS. 4 and 5 depict a preferred embodiment of the gas burner 14according to the invention.

[0036] The generally annular gas burner 14 comprises a posterior heatingplate 30, with holes through which gas can flow, such as the hole 31,distributed over its surface. As shown in FIG. 4, for example,approximately 60 to 80 radial rows of five holes can be provided and beformed in a posterior heating plate 30 that is relatively thick and inwhich the length of the holes 31 through which gas can flow exceedstheir diameter.

[0037] The posterior heating plate 30 closes off an annular cavity 32 ofa burner body 33 delimited by a hemispherical peripheral wall 34 and bya coaxial tubular central wall 35. The tubular central wall 35 defines acrossing central passage 36, through which passes the pipe 17 forevacuating burned gases which is not shown in FIGS. 4 and 5 but hasalready been referred to with reference to FIGS. 1 to 3.

[0038] The posterior heating plate 30 comprises at least one ignitionelectrode 37 and one flame control electrode 38.

[0039] The annular cavity 32 of the burner body 33 communicates with thesupply pipe 16, part of which is depicted in FIGS. 4 and 5.

[0040] The electrodes 37 and 38 are advantageously connected to acontrol device, not shown, by respective connecting lines 39 and 40disposed inside the supply pipe 16.

[0041] As can be seen in FIGS. 1 to 3, the annular gas burner 14 isoriented with its axis substantially horizontal and perpendicular to theadjacent peripheral wall 7 or back wall of the oven. The pipe 17 forevacuating burned gases therefore has a first section passing coaxiallythrough the central passage 36 of the gas burner 14, so that the burnedgases exhaust axially away from the adjacent peripheral wall 7 and arethen guided toward the upper portion of the oven in the burned gasesevacuation pipe 17.

[0042] Means for receiving the food to be cooked are also providedinside the muffle 1. In the embodiment depicted in the figures, acooking volume 81 is reserved inside the interior cavity 8 of the muffleto receive food to be cooked, and a simple frame is provided to supportremovable shelves, adapted to enter the muffle through the door providedin the anterior peripheral wall 6. The shelf support frame comprisesuprights connected by top crossmembers to constitute an open andgenerally parallelepipedal structure allowing free circulation of airinside the oven. The shelf support frame structure carries lateralslideways, for example in the form of U-shaped profiles, perpendicularto the anterior peripheral wall 6, and conformed to receive in a slidingfashion and to support the lateral edges of horizontal shelves on whichfood to be cooked can be placed.

[0043] The convection turbine 9 and the gas burner 14 are placed in themuffle 1 in direct communication with the cooking volume 81, with noseparating wall opposing the flow of air. There is merely provided amechanical protection grid 22, which is conformed and interposed betweenthe cooking volume 81 and the combination of the convection turbine 9and the gas burner 14, to prevent mechanical contact of a user's handwith the blades of the rotating turbine or with the gas burner 14. Thus,the mechanical protection grid 22 is placed on the upstream side of thegas burner 14. The mechanical protection grid 22 is of closed andenveloping cylindrical shape, with a cylindrical peripheral portion 23and a plane front portion 24. The mechanical protection grid 22 has meshsize that is sufficiently large not to impede the flow of air toward oraway from the convection turbine 9, and sufficiently small for a user'sfingers not to pass through them and to encourage the distribution ofthe convection air flow around the gas burner 14.

[0044] In the embodiment shown, the central region of the front portion24 of the mechanical protection grid 22 carries a filter 29 or a grid offiner mesh, encouraging a more regular flow of convection air around thegas burner 14 to stabilize the flame.

[0045] Clearly, in the oven structure as defined above, the airdischarged radially by the convection turbine 9 is guided only by theperipheral walls of the muffle 1, and is distributed more freelythroughout the cooking volume 81. This achieves more even cooking.

[0046] Simultaneously, there is nothing to oppose the free movement ofsplashed food particles that come from the food to be cooked in thecooking volume 81 and that can propagate into the whole of the interiorcavity 8 of the muffle 1, and especially toward the convection turbine 9and the gas burner 14. However, the free flow of air produces an effectof self-cleaning of the oven, and the particles do not remain in thearea occupied by the convection turbine 9 and the gas burner 14.

[0047] To assure good convection of air, a convection turbine 9 with agenerally cylindrical structure can advantageously be used, with aposterior flange 25 in the shape of a disc carrying a plurality of shortblades 26 at the front and distributed around its periphery. Thediameter D of the convection turbine 9 is preferably more than one thirdof the larger dimension (width or height) of the adjacent posteriorperipheral wall 7.

[0048] In the embodiment depicted, the convection turbine 9 has at leasttwelve blades 26 at the front that have a radial dimension less than onetenth of its diameter D.

[0049] The embodiment depicted further comprises a cleaning device 27that sprays water into the muffle 1.

[0050] The cleaning device 27 can comprise a horizontal cup adjacent thecenter of the upper ceiling wall 3, with central water supply means toproduce a flow of water toward the periphery of the cup, parallel to theupper ceiling wall 3. The water is sprayed radially at the periphery ofthe cup, preferably when the oven is still relatively warm, and thewater then flows over all of the peripheral walls of the oven as well asover the convection turbine 9 and the heating means.

[0051] The means according to the invention assure correct cooking notonly by simple convection of hot gas, but also mixed cooking in thepresence of steam.

[0052] The invention can provide better control of combustion bysupplying the gas burner 14 with an appropriate mixture of gas and airat a particular pressure. To this end, a device for producing blown air16 a (FIG. 3) is connected into the supply circuit 16 of the gas burner14, on the upstream side, to supply the gas burner 14 with blown air.The power of the device for producing blown air 16 a is advantageouslyadjustable.

[0053] The present invention is not limited to the embodiments that havebeen described explicitly, but includes variants and generalizationsthereof within the scope of the following claims.

1. Forced convection gas oven for cooking food, the oven comprising: amuffle with a generally parallelepipedal interior cavity delimited by alower floor wall, an upper ceiling wall and four peripheral walls, atleast one of the peripheral walls being provided with an access door forentry of food to be cooked into the interior cavity of the muffle andits exit therefrom, a centrifugal convection turbine, driven in rotationby a motor, disposed in the interior cavity of the muffle in thevicinity of the center of an adjacent peripheral wall with no accessdoor, mounted to rotate about a rotation axis perpendicular to theadjacent peripheral wall, and adapted to aspirate air axially toward thecenter of the adjacent peripheral wall and to discharge it radiallytoward the edges of the adjacent peripheral wall, a gas burner placedaxially in the aspiration inlet of the convection turbine, and adaptedto heat the air that is propelled into the muffle by the convectionturbine to cook the food, a cooking volume, reserved in the interiorcavity of the muffle to receive food to be cooked; wherein the gasburner is directed toward said peripheral wall of the oven, the gasburner is directed toward the center of the convection turbine.
 2. Ovenaccording to claim 1, wherein the convection turbine has a generallycylindrical structure, with a posterior flange carrying a plurality ofshort blades at the front and distributed around its periphery.
 3. Ovenaccording to claim 2, wherein the diameter of the convection turbine isgreater than one third of the larger dimension of the adjacentperipheral wall.